Yu joined Facebook almost five years ago. While there, he was responsible for corporate comms as Facebook transitioned from a private to public company.

Before Facebook, Yu worked at Google, MWW and Cisco.

In February, former Twitter comms vice-president Garrett teamed up with Barker, former director of global comms and public policy at Facebook, and O'Shaughnessy, former head of global comms at Skype, to launch an agency. They revealed the firm's name a month later on Tumblr.

The trio has previously worked with Yu, said Garrett.

'I think this is a strong recognition of our model and what we are trying to create, that Yu's experience and the respect he brings are joining us,' said Garrett. 'As we grow, we are looking for other Larrys.'

In his Facebook post, Yu wrote: 'Nearly five years ago, I joined some friends at a privately held company called Facebook to help a small team scale and expand upon the company's story. That journey was, in a word, crazy. And fun. Terrifying. And gratifying. So I'm off to do it again.'